In the field of display, the display panel of a flat panel display device (e.g., a liquid crystal display device or a light emitting diode display device) comprises an array substrate and an opposite substrate. The array substrate has data lines and gate lines arranged to intersect with each other. The data lines and the gate lines constitute a plurality of display units. A common signal line is formed surrounding the data lines and the gate lines. The array substrate is further formed with a repair line for repairing open circuit or short circuit trouble of the data lines, the gate lines or other signal lines. For example, the array substrate as shown in FIG. 1 comprises a plurality of data lines 11, a plurality of gate lines 12, a common signal line 13 and a repair line 14. The common signal line 13 and the repair line 14 are annular signal lines, and the repair line 14 is electrically connected with the common signal line 13 through an anti-static ring 15. The repair line 14 intersects with and is insulated from the data lines 11. In detection after the cell-forming process, if a certain data line 11 encounters open circuit or short circuit trouble, the maintenance personnel can repair this open circuit or short circuit data line 11 using the repairing line 14. For instance, if open circuit occurs to a certain data line 11, laser welding can be performed to the overlapping positions of this data line 11 with the repairing line 14 respectively, in this way, the data signal will be transmitted through the repair line 14. Certainly, open circuit of one data line 11 can be repaired only using half of an annular repair line 14, the other half of the annular repair line 14 can be used to repair open circuit for another data line 11, thus each repair line 14 can resolve open circuit problem for two data lines 11.
However, for the above array substrate, electrostatic charges generated during the normal operation of the display panel or in the manufacturing process of the display panel may enter the interior of the display panel through the repair line 14. For example, when plasma of high temperature and high energy bombards the surface of the array substrate, the electrostatic charges may be generated and aggregated on the common signal line 13, or the electrostatic charges may be aggregated on the peripheral common signal line 13 in the process of high speed transmission of the array substrate. The common signal line 13 may apply an electrostatic effect on the repair line 14 through the anti-static ring 15, which results in damage of nodes and devices within the display panel. When the electrostatic charges are accumulated to a certain degree, it may even break down the devices within the display panel, which results in defects of the display panel, thereby reducing yield of the display panel.